The invention relates to a steering knuckle with a hub for receiving a wheel bearing and with a bracket for fixing a control arm, especially a telescopic strut, wherein the bracket is formed on an arm projecting from the hub.
The general problem in such a steering knuckle is that on the one hand it should be very light, so that the non-dampened mass of the wheel suspension system is as small as possible and that on the other hand a high rigidity has to be provided, as all the forces for the longitudinal and transversal deceleration of the vehicle and of course the weight of the vehicle act on to it. The compromise realized up to now consists in a steering knuckle, which is made from a steel casting or iron casting.
One example for this is disclosed in DE-OS 26 24 704 A1. The casting has a hub, from which several arms project. One arm extends upwards and ends in a bracket, on which the lower end of the telescopic strut is fixed by means of two pins. To achieve the required rigidity the arm has a V-shaped cross-section.
DE 43 13 624 A1 discloses a steering knuckle made by a metal punching method. The advantage, named, compared to the casted or forged steering knuckle is the achievable weight reduction. The steering knuckle is substantially U-shaped, wherein the open side points to the vehicle. At the lower portion it is formed square for receiving a bearing, that means the legs abut approximately perpendicular the bottom of the U. The upper portion forms an arm for connecting a transverse control arm and has a semicircular cross-section. A recipient mounted there, for the ball pin of the transverse control arm has correspondingly the form of a half disc and is retained by a pin between the legs.
A similar embodiment can be taken from DE 195 33 315 C1. In this embodiment the open side of the U-shaped steering knuckle is closed by a tab and therefore is additionally reinforced. Therefore, an arm closed on all sides, is achieved.
It has been already proposed, inter alia in DE 196 53 542 A1, to use steel or iron-light weight metal alloys, such as aluminum. This material has on the one hand the advantage to be light, but also has the disadvantage of not being sufficiently rigid. Therefore, in the unexamined publication it is proposed, that the core of the steering knuckle is formed from light weight metal of higher strength as a hollow body with defined wall-thickness. Furthermore, it is clearly visible, that the manufacturing processes, necessary, are quiet cumbersome.
Therefore, the invention is based on the object, to provide a steering knuckle as light as possible, preferably made from a light metal alloy, which is simple to manufacture and having a sufficient strength a good rigidity.
In a first preferred embodiment, the steering knuckle is formed in such a way that the arm is formed by an approximately perpendicular bracket wall on whose side facing toward the vehicle the bracket is formed, and that a bridge extends between the outer end of the bracket wall and the hub, wherein the space between the bracket wall and the bridge is open to the side, i.e., open in the circumferential direction of the hub.
It has been found that because of this arrangement a high strength can be achieved, which especially can be referred back to the fact, that this arrangement is open in the circumferential direction compared to an arrangement, in which the arm has a U-shape and is open towards the vehicle. Furthermore, it has been found that the fatigue durability is increased and a compact design can be realized.
A second preferred embodiment consists of a hub that merges on the control arm side in a partial sleeve, wherein the bracket wall extends from the free end of the partial sleeve. Furthermore, one of the open sides of the chamber can be closed by a transverse wall, wherein this wall continues in a partial face on the hub, on which a bracket for fixing a brake caliper is provided.
Advantageously, the transverse wall is inserted in such a way, that its closed side extends in the driving direction, so that the arm thus formed is open to the rear in respect to the driving direction.
To be able to attach a steering rod to the steering knuckle, a support wall extending approximately horizontal is formed at the lower side of the hub or the partial sleeve, on which free end a fixing eye for the steering rod is provided. An extension of the bracket wall extends along the partial sleeve and joins perpendicularly the support wall.